Some embodiments of the disclosed apparatus are related to a class of Venturi tube wave energy converters (“Venturi WECs”) that operate by using the vertical (heave) component of wave motion to drive the vertical movement of an appropriately shaped tube suspended a significant distance beneath the surface of the water, where water is relatively unaffected by wave motion. The vertical movement of the tube through relatively still water causes water in the tube to transit from one side of a constriction in the tube to the other, producing a flow of water through the constriction whose velocity is amplified relative to the wave motion. By placing a hydrokinetic apparatus (e.g. a turbine) in or near the constriction and connecting this apparatus to conversion equipment (e.g. electrical generation equipment), wave energy can be efficiently converted to a useful form.